GHS Strings 615 12-String Set Phosphor Bronze Acoustic Guitar Strings, Light Model: 615 Featuring Nitro-Pack singles, guaranteed to be fresh from the factory! Copper-Tin-Phosphor alloy on a Hex Core Increased brightness & flexibility with a high end shimmer Light Gauge: 011(2)-014(2)-020/009-030/012-040/016-048/026